Library damaged error message

Hi,

I’m updated my MacOS system from Mountain Lion to Sierra after which my endnote 4 would not work, so had to update to Endnote 8. Now my library starts opening but then I get an error message "  This library is currently being used by someone else.  Try opening it again later" .  I have reinstalled endnote multiple times, I’ve “Recover library” multiple time and save under various names and restarted my computer multiple times. Still getting the same message. Only good thing at the moment is that endnote is not crashing anymore. If anyone has any other suggestions, please let me know, it would be greatly appreciated. Thanks

Alicia